The present invention relates to rotary regenerative heat transfer devices and, more particularly, to air preheaters wherein the individual heat transfer elements are stacked in open baskets which, in turn, are disposed in compartments in the rotor of the transfer device.
Air preheaters utilize the heat that would otherwise be lost out the smoke stacks of industrial and central power station boilers. In the preheater, this waste heat is captured before it reaches the stack and is transferred to the incoming cold air. Thousands of specially formed steel sheets--called heat transfer elements--absorb the waste heat from hot gases flowing through one half of the preheater structure--and release it to the incoming cold air as it passes through the other half of the structure. The heat transfer elements are spaced and arranged in a cylindrical shell called the rotor. The spaces between the elements allow the air and gas streams to flow across the surface of each sheet. The rotor revolves slowly within the preheater structure, carrying the elements alternately through the air and gas streams so that there is a continuous transfer of heat.
In use, heat transfer elements suffer, to a greater or lesser extent, from corrosion which ultimately necessitates their replacement. As a means of facilitating the efficient removal and replacement of the heat transfer elements in an air preheater, it is the common practice to stack the individual elements in baskets which are inserted into compartments formed in the rotor. The most common method of installing these baskets in the rotor compartments involves field welding attachment lugs to the corners of the basket, passing a chain or rope through the lugs, and then pulling the basket into position with a pulley, winch or pneumatic tugger. Alternatively, the basket may be pushed into position with a pneumatic or hydraulic ram device. Both of these installation methods, however, are time-consuming, resulting in excessive amounts of costly equipment downtime.
It is, therefore, a primary object of the present invention to provide an element basket, for an air preheater or similar heat transfer device, which may be readily installed in the preheater rotor and to further provide a method for the ready installation of the element basket. It is a further object to provide such an element basket which is inexpensive and is compatible with existing heat transfer devices.
The foregoing and other objects as may hereinafter appear are achieved by an element basket which includes a tubular structural element disposed in each of the four corners of the basket frame and extending therethrough in mutually parallel relation. During installation of the basket into the preheater rotor, rods are provided, each having an attachment member formed in one end. The rods are inserted into the tubular elements and retaining clamps are attached thereto to prevent withdrawal. A chain or rope is attached to the attachment members, thus allowing the basket to be conveniently drawn into a desired position in the rotor. The need for welding of attachment lugs is thus eliminated resulting in a significant reduction of installation time. Further, the tubular elements replace solid rod elements heretofore employed in the basket structure, thereby effecting a material cost reduction.